1. Technical Field
The invention relates to mounts for electronic components.
In particular, the invention relates to a dimensionally precise mount for an electronic component wherein the component has a mounting base defining one electrical node, and at least one protruding wire defining another electrical node, wherein the electronic component is precisely indexed in relation to electrical terminals and an insulative base.
The invention further relates to a dimensionally precise mount for an electronic component wherein bending moment applied to a wire protruding from the electronic component is minimized in assembly and use.
2. Prior Art
The operative elements of electronic components such as tantalum capacitors, semiconductor diodes, transistors, monolithic integrated circuits, resistors, inductors and the like are generally enclosed, as is well known in the art, within physically handleable packages or mounts suitable for physical emplacement upon and electrical connection to hybrid substrates, printed-circuit boards and the like. Such mounts are particularly necessary where microminiature components have easily damaged protruding wires or surfaces easily contaminated in handling.
Many types of such electronic components, exemplified by the tantalum capacitor, comprise a component body, such as the tantalum capacitor cathode, having a solderable or electrically conductive surface definable as a mounting surface, and at least one protruding wire, such as the tantalum capacitor anode riser, which in use extends laterally in a direction essentially parallel to the mounting surface. Semiconductor devices commonly have one electrical node comprising a mounting surface, and from an obverse surface one or more wires protruding laterally or disposed laterally from an initial protrusion orthogonal to the mounting surface.
Prior-art mounts for tantalum capacitors typically comprised a cathode terminal soldered in imprecise spatial relationship to the mounting surface, and an anode terminal or cap having a central hole through which the relatively rigid anode riser wire was passed using hand-assembly methods. The central hole was necessarily larger than the diameter of the anode wire, to permit passage therethrough, and therefore when the anode riser wire was welded to the larger-diameter periphery, the weld occupied only a small portion of the respective peripheries, causing yield losses due to cold welds or burnt welds. Welding problems also arose because the anode riser wire, typically composed of metallic tantalum, had a substantially higher melting point than the metal from which the anode terminal or cap was fabricated, and because of substantial differences in thickness between the anode riser wire and the relatively thin anode terminal.
A polymer typically was injected to fill voids in the tantalum capacitor mount structure, and an outer covering applied. Because the physical dimensions and locus of the tantalum capacitor within the prior-art mount structure was subject to wide manufacturing variations, it was necessary that the overall mount be substantially larger than the size minimally necessary to accomplish its function.
Tantalum capacitors, because of the nature of their fabrication, have an annular region adjacent the juncture of the anode riser wire and the body of the capacitor covered by an easily fractured, brittle insulating layer, typically tantlum pentoxide. Prior art methods of welding and assembling terminals to said anode riser wire frequently imposed destructive bending moment during assembly, or stresses which eventually resulted in shorts due to fracturing of the fragile annular insulating layer.
Similarly, semiconductor devices having protruding wire leads are prone to microscopic fracturing stresses from bending or flexure of said leads during and after assembly. Prior-art mounts or packages for such semiconductor devices resorted to relatively long, flexible wire leads, and wide, conservative space tolerances, with the result that most mounts or packages for semiconductors are substantially larger than needed simply to contain and provide terminal access to the semiconductor device.
It is therefore an object of the invention to provide a component mount and method of assembling same inherently capable of greater mechanical dimension precision than that of the prior art.
It is another object of the invention to provide a dimensionally precise electronic component mount having size and terminal disposition independent of expected variations in production dimensions of the electronic component.
A further object of the invention is to provide a dimensionally precise electronic component mount wherein bending moment or flexure of component wire leads is minimized during and after assembly.
Another object of the invention is to provide a dimensionally precise electronic component mount having reduced susceptibility to cold or burnt welds between component wire leads and electrical terminals.
A still further object of the invention is to provide a dimensionally precise electronic component mount suitable for iterative assembly along a continuous web.
Yet another object of the invention is to provide a dimensionally precise electronic component mount having rigid support for an electronic component mounting surface.